Charge transport in conducting polymers and single-walled carbon nanotubes
is studied by means of complex dielectric spectroscopy down to 2 K. The neg
ative dielectric constants, low plasma freqeuncies, and anomalously long re
laxation times can be understood in terms of a low density of delocalized s
tates near the Fermi level, which stems from the competition between disord
er-driven localization and interchain charge transfer.